The present invention relates, in general, to information processing systems and in particular to information storage devices within information processing systems. More particularly, the present invention relates to problems associated with effectively writing information onto the magnetic media used in information storage systems as the bit densities and coercivity of the magnetic media continue to increase.
The requirement for high density magnetic storage of data on hard disk drives has been increasing every year. Development of magnetoresistive (MR) sensors (also referred to as heads) for disk drives, in the early 1990""s, allowed disk drive products to offer maximum storage capacity with a minimum number of components (heads and disks). Fewer components has translated to lower storage costs, higher reliability and lower power requirements.
In principle, shrinking the data into ever-decreasing areas is the key to providing increased storage within an information storage system. However, it turns out to not be that simple. In order for the read/write system to work reliably, the magnetic fields that the stored data produce must be large enough to generate a measurable electrical signal in the head in read mode, so that the stored information can be retrieved. This means that there is a basic limit to how much you can shrink the area where each byte is to be stored. Try to pack the data into too small an area and you risk not being able to retrieve it. Effectively then, the number of bytes that can be packed onto an information storage system is limited by how sensitive the read/write head is to the magnetic fields produced by those bytes. Additionally, the ability of the read/write head to precisely apply a sufficient magnetic field to such a small area such that the read/write head, in write mode, is capable of flipping the bits therein to write the information is a further consideration of space allocation.
The development of Giant Magnetoresistive (GMR) Heads has promised to revolutionize the design of read/write heads within the next few years. The magnetoresistive materials which make up GMR heads are capable of generating electrical signals which are hundreds of times larger than those generated by conventional magnetic materials when they are put in the same magnetic field. This GMR effect makes materials extremely sensitive to the magnetic fields stored on an information storage system which in turn allows data to be stored in much smaller areas while still making the information easily retrievable.
With the read problem solved by GMR heads, problems still exist in writing information in ever-decreasing areas. Usually, information is written by an inductive recording head where a current is passed through a magnetic core to produce a magnetic field. The generated magnetic field is then applied across a fine air gap between the core and the magnetic media to enable each bit to be appropriately flipped.
As the capacity, or bit density, of the magnetic media is increased, the coercivity of the magnetic media must also be increased. The goal of increasing the coercivity of the magnetic media is to prevent such effects as superparamagnetic limit, media noise, etc. As a result of the increase in coercivity of the magnetic media, the magnetic field required to reverse the magnetization direction of a bit is increased. In order for an inductive recording head to effectively write on the high coercivity media, the inductive recording head must generate a stronger magnetic field. Hence, the current required to write information has to be substantially increased.
The need for such a substantial current has a variety of problems associated with it. First, the high current requirement results in increased power dissipation in the write coils of the inductive recording heads. Second, the eddy current losses in the magnetic core increase due to the larger fields and further due to the trend towards higher frequency operation. Third, the size and complexity of the inductive recording heads, and their associated write coils, necessary to produce the required magnetic fields are substantial barriers to their standardization.
Therefore, it is desirable to provide a method for writing information on high bit density, and therefore high coercivity, magnetic media which will not experience the problems of increased power dissipation, eddy current losses, or the size and complexity issues present in current inductive recording head technology. Solving the problems presented by current technology will allow further advances in data storage technology including greater capacity, faster read and write times, continued miniaturization of components, lower power needs as well as many other benefits.
The present invention overcomes the limitations of presently used read/write heads by creating a magnetic field about a capacitive element capable of being focused and strengthened such that information can be effectively written onto high bit density hard disk drives.
In one form, the invention relates to a read/write apparatus for reading/writing information on a magnetic medium comprising a capacitive element capable of generating a magnetic field for writing information onto a magnetic medium and a cooling apparatus, operably associated with the capacitive element, capable of cooling the capacitive element to a sub-ambient temperature.
In another form, the invention relates to a method for writing information on a magnetic medium comprising creating a magnetic field, about a capacitive element, capable of writing information on a magnetic medium and cooling the capacitive element to a sub-ambient temperature.
In yet another form, the invention relates to an information storage system comprising a magnetic medium, a read/write apparatus operably associated with the magnetic medium for reading/writing information on said magnetic medium comprising a capacitive element capable of generating a magnetic field for writing information onto the magnetic medium and a cooling apparatus, operably associated with the capacitive element, capable of cooling the capacitive element to a sub-ambient temperature.
In a particularized form, the present invention writes information onto magnetic media by employing a thin-film capacitor structure coupled to a voltage source. The thin-film capacitor has a few nanometer thick dielectric made of a magnetoelectric material such as Cr2O3. In order for the thin-film capacitor structure to perform optimally, the thin-film capacitor structure is cooled to a temperature of 255 K. As voltage is applied to the thin-film capacitor having a magnetoelectric material dielectric, a magnetic field is produced which is then applied to a magnetic media enabling the writing of data thereon.
These and other features of the invention will be more clearly understood and appreciated upon considering the detailed embodiments described hereinafter.